Yunhai-1 was carried by a Long March-2D rocket, the 240th mission for the Long March rocket family.

Yunhai-1 meteorological satellite. Image Credit: Xinhua

Developed by the Shanghai Academy of Spaceflight Technology, the satellite will be used for observation of atmospheric, marine and space environment, disaster prevention and mitigation, and scientific experiments.

Image above: One of the first proton-lead events at 5.02 TeV as seen by ALICE in November 2016 (Image: CERN).

Following seven successful months of colliding proton beams with each other in the search for new fundamental particles, the LHC today began colliding proton beams with beams made up of heavy ions – the nuclei of lead atoms.

The study of these asymmetric collisons will give physicists more precise insights into the state of the universe a few millionths of a second after the Big Bang.

During this brief period, the universe was filled with all kinds of particles moving about at near light speed. The mixture was dominated by quarks –fundamental units of matter – and by gluons, carriers of the strong force that normally bind quarks into familiar protons and neutrons. In those first moments of extreme temperatures and densities, protons and neutrons had not yet formed and the quarks and gluons were bound only weakly, free to move on their own in what’s called a quark-gluon plasma.

Normally, physicists recreate these conditions by colliding two beams both made up of the same type of heavy ions, such as lead.

Image above: While all the experiments will take some data, the lower energy run is being conducted mostly for the scientists at CERN’s ALICE experiment, who want to collect much more data, at higher precision than in 2013. (Image: Sophia Bennett/ CERN).

But one night in September 2012, LHC physicists chose to collide beams made of two different particles for the first time – heavy ions with the less-massive protons. Analysing the data, the researchers were surprised to see in a fraction of the collisions signs of a collective expansion of the system, a sort of mini-Big Bang. This is a characteristic hallmark of lead-lead collisions, and well known to be associated with the properties of quark-gluon plasma, but it had never been seen in lead-proton collisions before.

Then, in 2013, a full month run of proton-lead collisions confirmed those first observations.

This year, proton and lead beams will be collided at two different energies: 5.02 TeV and, later in the month, the maximum possible 8.16 TeV. The lower energy will be equivalent to that of the lead-lead collisions in 2015, the earlier proton-lead collisions and also some proton-proton collisions, meaning researchers will be able to make direct comparisons between all three.

“Proton-lead collisions are something the LHC was not originally foreseen to do, but now it has even higher physics interest than had been expected. All the experiments have joined the programme, including LHCb which originally wasn’t a heavy-ion experiment,” says John Jowett, the CERN accelerator physicist responsible for heavy ions in the LHC.

While all the experiments will take some data, the lower energy run is being conducted mostly for the scientists at CERN’s ALICE experiment, who want to collect much more data, from more events and at higher precision, to get better statistics than in 2013.

“We’re very excited by the possibility in this run of understanding a completely new facet of this phenomenon. Understanding how strongly interacting matter behaves in the simpler proton-lead system could actually hold the key to understanding how the quark-gluon plasma is formed” explains Federico Antinori, spokesperson-elect for CERN’s ALICE experiment.

Image above: Event displays from the proton-lead run, January 2013, generated by the High Level Trigger (HLT) of the ALICE experiment. (Image: CERN).

Lead ions have 82 times the charge and are 206.4 times more massive than protons. Colliding these asymmetric beams, with very different properties and lifetimes, leads to many challenges for the LHC accelerator physicists and operators. A great deal of preparatory engineering work was done in last week’s technical stop including special modifications to the LHC’s beam instrumentation and the systems which inject the beam.

“It was thought that this wouldn’t work at all, as particles of different types move around the LHC at different speeds – at injection energy the lead beam is slightly slower than the protons so makes seven fewer turns around the ring in a minute (the protons make 674,729 in that time). Those problems were solved in 2012 but the beam physics and operational set-up remain complicated and somewhat unexplored territory.” Jowett says.

“This is the first time we’ve done lead-proton collisions since 2013, providing data that is important for interpreting the results of the lead-lead collisions,” says Frédérick Bordry, CERN’s Director for Accelerators and Technology. “It’s also the last ion run until 2018.”

Note:

CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 22 Member States.

“Congratulations to the entire mission team. ULA is honored to celebrate the successful launch of the WorldView-4 satellite for DigitalGlobe and Lockheed Martin,” said Gary Wentz, ULA vice president of Human and Commercial Services. “This morning’s Atlas V launch delivered the WorldView-4 satellite into near sun-synchronous orbit during a flawless flight. ULA is proud to have launched the entire constellation of DigitalGobe’s satellites and served in an essential role to get this revolutionary capability to orbit.”

This mission was launched aboard an Atlas V 401 configuration vehicle, which includes a 4-meter-diameter large payload fairing. The Atlas booster for this mission was powered by the RD AMROSS RD-180 engine and the Centaur upper stage was powered by the Aerojet Rocketdyne RL10C engine.

Today’s launch marks ULA’s ninth launch in 2016 and the 112th successful launch since the company was formed in December 2006,” said Wentz. “Thank you to the men and women at the 30th Space Wing who worked tirelessly to combat and contain the fires that delayed a launch attempt in mid-September.”

Atlas V WorldView-4 Launch Highlights

On Sept. 15, wildfires spread through Vandenberg Air Force Base’s South Base. The wildfires delayed the Sept. 16 launch attempt. ULA, the Western Range and DigitialGlobe worked together to achieve today’s launch success.

Including today’s seven successful CubeSat deployments, ULA has launched 62 CubeSats. Sponsored by the NRO, today’s CubeSat payloads are unclassified technology demonstrations known collectively as Enterprise. The CubeSats rode in the Aft Bulkhead Carrier, developed by the NRO and ULA, on the Centaur upper stage.

ULA has established a very low-cost approach to both design and launch of CubeSats to enable the ability to accommodate our commitment to education and innovation. This fall ULA announced the winner of its first-ever CubeSat competition this fall. Dubbed CubeCorps, the program encourages hands-on science, technology, engineering and math (STEM) experience to motivate, educate and develop the next generation of rocket scientists and space entrepreneurs.

ULA's next launch is the GOES-R satellite for NASA. The launch is scheduled for Nov. 19 from Space Launch Complex-41 at Cape Canaveral Air Force Station, Florida.

DigitalGlobe’s WorldView 4 satellite. Image Credit: Lockheed Martin

With more than a century of combined heritage, United Launch Alliance is the nation’s most experienced and reliable launch service provider. ULA has successfully delivered more than 100 satellites to orbit that provide critical capabilities for troops in the field, aid meteorologists in tracking severe weather, enable personal device-based GPS navigation and unlock the mysteries of our solar system.

Down on Earth, everyone knows to remove batteries from electrical goods before recycling. When it comes to disposing of satellites in orbit, the same principle holds true: charged batteries or leftover fuel have been known to trigger breakups, a major source of space debris.

ESA’s Clean Space initiative, tasked with reducing the impact of Europe’s space industry on the terrestrial and space environments, is investigating novel methods of satellite ‘passivation’ – ensuring that a mission reaching the end of its working life has no remaining energy sources that might risk a break-up.

ESA has identified ways to ‘passivate’ satellites through its CleanSat programme, developing building block technologies to ensure future satellite platforms can meet debris regulations in a practical way, without unduly affecting their market competitiveness.

Satellite break-up

“Once a derelict satellite goes out of control, it can drift into orbital and altitude states beyond its design parameters, potentially raising its temperature significantly,” explains Luisa Innocenti, heading Clean Space. “Sustained temperature rises would be bad news for propellant tanks and batteries.”

Any leftover propellant may split into its component chemicals and push up the tank pressure. In the case of popular satellite monopropellant hydrazine, this splitting process generates yet more heat, causing a chain reaction that could continue until a tank breaks apart.

And even if a tank holds together, the potential is still there for fragmentation should it ever be struck in a hypevelocity impact by a piece of debris.

Batteries are also vulnerable to heating. Kept above 100ºC for a long time, even inactive batteries are at risk of ‘thermal runaway’, with chemical reactions giving rise to even more heat. If batteries are inadvertently left live, then overcharging can also give rise to break-ups.

Adding to the challenge, batteries may also be vulnerable to radiation in some medium-altitude orbits, which can degrade the reliability of electrical components.

Passivation

“Some satellites left in graveyard orbits above geostationary orbit will need to remain stable for hundreds of years,” adds Luisa. “It is extremely difficult to say if a battery can really remain in a safe state for such a prolonged period, and harder still to test it.”

Steps towards safety

Ideally, propellant tanks would be fully vented by firing the satellite’s thrusters while still under full control, but this is not feasible once the pressure drops below a certain level. The current backup is ‘passivation valves’, which are opened only at mission end.

But these pyrotechnic valves are only qualified for a maximum of eight years in space, whereas passivation is normally carried out after 10–15 years.

European Battery Test Centre

Luisa explains: “As an alternative, we’re applying a novel development from material science: shape memory alloys, which can change into a preset shape through heating. At the mission end, the actuator’s shape would be changed to break open a valve and, once opened, the valve will stay open.”

So far, these shape-memory alloy valves have been subjected to system studies and materials tests; the next stage will be to qualify them for use in satellites.

Shape memory alloy valve

On the battery side, the latest Li-ion battery designs already include various protections such as venting systems to release pressure. The best protection is ensuring batteries are completely discharged, requiring much higher temperatures to kick-start hazardous ‘exothermic’ reactions.

“Up until now, end-of-life passivation has been performed by electronics, but considering the harsh space environment this cannot be considered a reliable situation in its own right,” adds Luisa.

Passivation methods

“Instead, CleanSat is looking at methods to physically isolate batteries from solar arrays or the rest of the power subsystem, such as relays, pyro-cutters and short-circuiting the arrays, attempting to use components that are less sensitive to the harsh space environment.”

These techniques will, of course, need to be tested against the harsh conditions seen by satellites after the end of mission, particularly through thermal cycling, to ensure that the proposed solution maintains its effect throughout the disposal phase.

The aim is to have such functions inserted as standard into future European-standard power control and distribution units.

About CleanSat:

This year, CleanSat has studied 28 building block technologies in dedicated small studies. Of these, the high-priority building blocks to be developed further will be presented to ESA’s Council at Ministerial Level next month.

jeudi 10 novembre 2016

(Highlights: Week of Oct. 31, 2016) - As three crew members made their return trip to Earth, investigations continued on the International Space Station including another successful creation on the station’s 3-D printer.

NASA astronaut Shane Kimbrough removed a two-piece print of a sample container and lid made out of high-density polyethylene plastic from the Additive Manufacturing Facility (Manufacturing Device), installed on the station in 2015. The Manufacturing Device is a 3-D printer that uses additive manufacturing to build a part layer by layer using an engineered plastic polymer as raw material. Kimbrough reported that the parts adhered well to the print surface, ensuring a solid build. Soon afterward, the ground team commanded the printer to use the same material to create another sample to learn about the plastic’s tensile strength.

Image above: A tiny bud is one of a handful of lettuce plants growing on the International Space Station as part of the Veg-03 investigation, finding better ways to grow fresh food in orbit so astronauts will have healthier sustenance on long space journeys. Image Credit: NASA.

The Manufacturing Device is another step toward a permanent manufacturing capability on the space station. It will enable the production of components and tools on demand in orbit, which will provide further research into manufacturing for long-term missions. The station crew can use it to print a variety of items to perform maintenance, build tools and repair sections in case of an emergency, leading to a reduction in cost, mass, labor and production time. Further research will also help develop this advanced technology for use on Earth.

Ground teams continued another round of the Advanced Colloids Experiment-Temperature Control (ACE-T-1) study. For decades, astronauts and scientists have studied complex structures with unique properties in space. The station's microgravity environment allows for the study of microscopic structures in three dimensions without the potentially distorting properties of gravity. The ACE-T-1 investigation examines tiny suspended particles designed by scientists to connect themselves in a specific way to form organized structures in water.

Kimbrough began his flight day 15 human research activities, by collecting blood and urine samples for the Biochemical Profile (Biochem Profile) investigation. The astronauts study themselves to learn how the human body reacts to long-duration spaceflight. Biochem Profile tests bodily fluid samples obtained from astronauts before, during and after spaceflight. Specific proteins and chemicals in the samples are used as biomarkers, or indicators of health. Post-flight analysis yields a database of samples and test results, which scientists can use to study the effects of spaceflight on the body. Establishing a chemical profile of the body’s response to spaceflight will help scientists understand how different systems in the body interact in microgravity in different groups of people. Scientists can also test the effectiveness of possible countermeasures like exercise and nutrition and their effects on crew health during long-duration exploration missions.

October Highlights

Video above: October saw three new crew members aboard a Soyuz spacecraft and a Cygnus resupply ship launch to the space station before another crew landed after 115 days in space. Video Credit: NASA.

An improved understanding of the biochemical effects of microgravity could help patients with limited mobility on Earth, such as those on bed rest. Understanding how various physiological systems respond and interact to changing gravity conditions could help physicians design different treatments or exercises for people with limited mobility.

While settling in to the space station, Kimbrough conducted other human research investigations this week, including Dose Tracker and Space Headaches.

Progress also was made on other investigations and facilities this week, including Veg-03, Meteor, ISS Ham, Group Combustion.

In a first-of-its-kind collaboration, NASA's Spitzer and Swift space telescopes joined forces to observe a microlensing event, when a distant star brightens due to the gravitational field of at least one foreground cosmic object. This technique is useful for finding low-mass bodies orbiting stars, such as planets. In this case, the observations revealed a brown dwarf.

Brown dwarfs are thought to be the missing link between planets and stars, with masses up to 80 times that of Jupiter. But their centers are not hot or dense enough to generate energy through nuclear fusion the way stars do. Curiously, scientists have found that, for stars roughly the mass of our sun, less than 1 percent have a brown dwarf orbiting within 3 AU (1 AU is the distance between Earth and the sun). This phenomenon is called the "brown dwarf desert."

Image above: This illustration depicts a newly discovered brown dwarf, an object that weighs in somewhere between our solar system's most massive planet (Jupiter) and the least-massive known star. Image Credits: NASA/JPL-Caltech.

The newly discovered brown dwarf, which orbits a host star, may inhabit this desert. Spitzer and Swift observed the microlensing event after being tipped off by ground-based microlensing surveys, including the Optical Gravitational Lensing Experiment (OGLE). The discovery of this brown dwarf, with the unwieldy name OGLE-2015-BLG-1319, marks the first time two space telescopes have collaborated to observe a microlensing event.

"We want to understand how brown dwarfs form around stars, and why there is a gap in where they are found relative to their host stars," said Yossi Shvartzvald, a NASA postdoctoral fellow based at NASA's Jet Propulsion Laboratory, Pasadena, California, and lead author of a study published in the Astrophysical Journal. "It's possible that the 'desert' is not as dry as we think."

What is microlensing?

In a microlensing event, a background source star serves as a flashlight for the observer. When a massive object passes in front of the background star along the line of sight, the background star brightens because the foreground object deflects and focuses the light from the background source star. Depending on the mass and alignment of the intervening object, the background star can briefly appear thousands of times brighter.

Image above: Two space-based telescopes teamed up with ground-based observatories to observe a microlensing event caused by a brown dwarf. Image Credits: NASA/JPL-Caltech.

One way to understand better the properties of the lensing system is to observe the microlensing event from more than one vantage point. By having multiple telescopes record the brightening of the background star, scientists can take advantage of "parallax," the apparent difference in position of an object as seen from two points in space. When you hold your thumb in front of your nose and close your left eye, then open it and close your right eye, your thumb seems to move in space -- but it stays put with two eyes open. In the context of microlensing, observing the same event from two or more widely separated locations will result in different magnification patterns.

"Anytime you have multiple observing locations, such as Earth and one, or in this case, two space telescopes, it's like having multiple eyes to see how far away something is," Shvartzvald said. "From models for how microlensing works, we can then use this to calculate the relationship between the mass of the object and its distance."

The new study

Spitzer observed the binary system containing the brown dwarf in July 2015, during the last two weeks of the space telescope's microlensing campaign for that year.

While Spitzer is over 1 AU away from Earth in an Earth-trailing orbit around the sun, Swift is in a low Earth orbit encircling our planet. Swift also saw the binary system in late June 2015 through microlensing, representing the first time this telescope had observed a microlensing event. But Swift is not far enough away from ground-based telescopes to get a significantly different view of this particular event, so no parallax was measured between the two. This gives scientists insights into the limits of the telescope's capabilities for certain types of objects and distances.

"Our simulations suggest that Swift could measure this parallax for nearby, less massive objects, including 'free-floating planets,' which do not orbit stars," Shvartzvald said.

Spitzer Space Telescope. Image Credit: NASA

By combining data from these space-based and ground-based telescopes, researchers determined that the newly discovered brown dwarf is between 30 and 65 Jupiter masses. They also found that the brown dwarf orbits a K dwarf, a type of star that tends to have about half the mass of the sun. Researchers found two possible distances between the brown dwarf and its host star, based on available data: 0.25 AU and 45 AU. The 0.25 AU distance would put this system in the brown dwarf desert.

"In the future, we hope to have more observations of microlensing events from multiple viewing perspectives, allowing us to probe further the characteristics of brown dwarfs and planetary systems," said Geoffrey Bryden, JPL scientist and co-author of the study.

Swift Space Telescope. Image Credit: NASA

JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena, California. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. NASA's Swift satellite was launched in November 2004 and is managed by NASA's Goddard Space Flight Center in Greenbelt, Maryland.

NGC 1222, seen in this image taken with the Wide Field Camera 3 on board the NASA/ESA Hubble Space Telescope is a galaxy with a rather eventful story to tell. NGC 1222 has been described as a peculiar example of a type of galaxy known as a lenticular galaxy.

Astronomers think that NGC 1222 is in the process of swallowing up two much smaller dwarf galaxies that strayed too close to it. It is likely that the encounter was the trigger for the starburst in NGC 1222, bringing in fresh supplies of gas that are now fueling the burst of star formation.

Typically, this kind of galaxy would present a rather smooth appearance on the sky and would consist mostly of old, reddish stars. A bit dull, perhaps. But NGC 1222 is certainly not a typical member of its class — and it’s anything but dull. Observations show the characteristic features of very recent star formation on a huge scale — an event known as a starburst. The reason for all this violent activity is caused by the fact that NGC 1222 is not alone. It actually contains three compact regions, each of which appears to be the central nucleus of a galaxy.

Hubble and the sunrise over Earth

Although its peculiarities were first seen in photographic images, these were not able to reveal the level of fine detail that can be recovered by Hubble. The image taken by Hubble allows us to see an astonishing amount of structure in this galaxy, emphasizing its colorful history. Against the smooth background of old stars that was the original lenticular galaxy, we can clearly see dark filaments of dust and bright filaments of gas, both associated with the powerful star formation process.

ESA’s Gaia is surveying stars in our Galaxy and local galactic neighbourhood in order to build the most precise 3D map of the Milky Way and answer questions about its structure, origin and evolution.

Launched in 2013, Gaia has already generated its first catalogue of more than a billion stars – the largest all-sky survey of celestial objects to date.

To achieve its scientific aims, it points with ultra-high precision, and to enable the control team to monitor spacecraft performance, Gaia regularly reports to the ground information about its current attitude and the stars that have been observed.

These engineering data have been accumulated over 18 months and combined to create a ‘map’ of the observed star densities, from which a beautiful and ghostly virtual image of our magnificent Milky Way galaxy can be discerned, showing the attendant globular clusters and Magellanic clouds.

Where there are more stars, as in the Galactic centre, the map is brighter; where there are fewer, the map is darker. The map includes brightness data corresponding to several million stars.

The moon is a familiar sight in our sky, brightening dark nights and reminding us of space exploration, past and present. But the upcoming supermoon — on Monday, Nov. 14 — will be especially “super” because it’s the closest full moon to Earth since 1948. We won’t see another supermoon like this until 2034.

The moon’s orbit around Earth is slightly elliptical so sometimes it is closer and sometimes it’s farther away. When the moon is full as it makes its closest pass to Earth it is known as a supermoon. At perigree — the point at which the moon is closest to Earth — the moon can be as much as 14 percent closer to Earth than at apogee, when the moon is farthest from our planet. The full moon appears that much larger in diameter and because it is larger shines 30 percent more moonlight onto the Earth.

Showstopper Nov. 14 Supermoon is the Closest Moon to Earth since 1948

Video above: The moon is a familiar sight, but the days leading up to Monday, Nov. 14, promise a spectacular supermoon show. When a full moon makes its closest pass to Earth in its orbit it appears up to 14 percent bigger and 30 percent brighter, making it a supermoon. This month’s is especially ‘super’ for two reasons: it is the only supermoon this year to be completely full, and it is the closest moon to Earth since 1948. The moon won’t be this super again until 2034! Video Credits: NASA Goddard/Clare Skelly.

The biggest and brightest moon for observers in the United States will be on Monday morning just before dawn. On Monday, Nov. 14, the moon is at perigee at 6:22 a.m. EST and “opposite” the sun for the full moon at 8:52 a.m. EST (after moonset for most of the US).

If you’re not an early riser, no worries. “I’ve been telling people to go out at night on either Sunday or Monday night to see the supermoon,” said Noah Petro, deputy project scientist for NASA’s Lunar Reconnaissance Orbiter (LRO) mission. “The difference in distance from one night to the next will be very subtle, so if it’s cloudy on Sunday, go out on Monday. Any time after sunset should be fine. Since the moon is full, it’ll rise at nearly the same time as sunset, so I’d suggest that you head outside after sunset, or once it’s dark and the moon is a bit higher in the sky. You don’t have to stay up all night to see it, unless you really want to!”

This is actually the second of three supermoons in a row, so if the clouds don’t cooperate for you this weekend, you will have another chance next month to see the last supermoon of 2016 on Dec. 14.

ScienceCasts: 2016 Ends with Three Supermoons

Video above: Nothing beats a bright and beautiful "supermoon." Except maybe, three supermoons! 2016 ends with a trio of full moons at their closest points to Earth. Video Credits: NASA.

NASA scientists have studied the moon for decades. A better understanding of our moon helps scientists infer what is happening on other planets and objects in the solar system. “The moon is the Rosetta Stone by which we understand the rest of the solar system,” Petro said.

LRO has been mapping the moon’s surface and capturing high resolution images for more than seven years. Extensive mapping of the moon aids scientists in understanding our planet’s history, as well as that of planetary objects beyond the Earth-moon system.

“Because we have the Apollo samples, we can tie what we see from orbit to those surface samples and make inferences about what has happened to the moon throughout its lifetime,” Petro said. “The samples tell us how old certain lunar surfaces are, and based on the number of impact craters on those surfaces, we can estimate the ages of the rest of the moon. Furthermore, we can then apply those models to estimate the ages of surface on other planets in our solar system — all by studying the moon!”

Astronomers may have solved the mystery of the peculiar volatile behavior of a supermassive black hole at the center of a galaxy. Combined data from NASA’s Chandra X-ray Observatory and other observatories suggest that the black hole is no longer being fed enough fuel to make its surroundings shine brightly.

Many galaxies have an extremely bright core, or nucleus, powered by material falling toward a supermassive black hole. These so-called “active galactic nuclei” or AGN, are some of the brightest objects in the Universe.

Astronomers classify AGN into two main types based on the properties of the light they emit. One type of AGN tends to be brighter than the other. The brightness is generally thought to depend on either or both of two factors: the AGN could be obscured by surrounding gas and dust, or it could be intrinsically dim because the rate of feeding of the supermassive black hole is low.

Some AGN have been observed to change once between these two types over the course of only 10 years, a blink of an eye in astronomical terms. However, the AGN associated with the galaxy Markarian 1018 stands out by changing type twice, from a faint to a bright AGN in the 1980s and then changing back to a faint AGN within the last five years. A handful of AGN have been observed to make this full-cycle change, but never before has one been studied in such detail. During the second change in type the Markarian 1018 AGN became eight times fainter in X-rays between 2010 and 2016.

After discovering the AGN’s fickle nature during a survey project using ESO’s Very Large Telescope (VLT), astronomers requested and received time to observe it with both NASA’s Chandra X-ray Observatory and Hubble Space Telescope. The accompanying graphic shows the AGN in optical light from the VLT (left) with a Chandra image of the galaxy’s central region in X-rays showing the point source for the AGN (right).

Data from ground-based telescopes including the VLT allowed the researchers to rule out a scenario in which the increase in the brightness of the AGN was caused by the black hole disrupting and consuming a single star. The VLT data also cast doubt on the possibility that changes in obscuration by intervening gas cause changes in the brightness of the AGN.

However, the true mechanism responsible for the AGN’s surprising variation remained a mystery until Chandra and Hubble data was analyzed. Chandra observations in 2010 and 2016 conclusively showed that obscuration by intervening gas was not responsible for the decline in brightness. Instead, models of the optical and ultraviolet light detected by Hubble, NASA’s Galaxy Evolution Explorer (GALEX) and the Sloan Digital Sky Survey in the bright and faint states showed that the AGN had faded because the black hole was being starved of infalling material. This starvation also explains the fading of the AGN in X-rays.

Chandra X-ray Observatory. Image Credits: NASA/CXC

One possible explanation for this starvation is that the inflow of fuel is being disrupted. This disruption could be caused by interactions with a second supermassive black hole in the system. A black hole binary is possible as the galaxy is the product of a collision and merger between two large galaxies, each of which likely contained a supermassive black hole in its center.

The list observatories used in this finding also include NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR) mission and Swift spacecraft.

Two papers, one with the first author of Bernd Husemann (previously at ESO and currently at the Max Planck Institute for Astronomy) and the other with Rebecca McElroy (University of Sydney), describing these results appeared in the September 2016 issue of Astronomy & Astrophysics journal.

Sharp new observations have revealed striking features in planet-forming discs around young stars. The SPHERE instrument, mounted on ESO’s Very Large Telescope, has made it possible to observe the complex dynamics of young solar systems — including one seen developing in real-time. The recently published results from three teams of astronomers showcase SPHERE’s impressive capability to capture the way planets sculpt the discs that form them — exposing the complexities of the environment in which new worlds are formed.

Three teams of astronomers have made use of SPHERE, an advanced exoplanet-hunting instrument on the Very Large Telescope (VLT) at ESO’s Paranal Observatory, in order to shed light on the enigmatic evolution of fledgling planetary systems. The explosion in the number of known exoplanets in recent years has made the study of them one of the most dynamic fields in modern astronomy.

Disc around the young star RX J1615

Today it is known that planets form from vast discs of gas and dust encircling newborn stars, known as protoplanetary discs. These can extend for thousands of millions of kilometres. Over time, the particles in these protoplanetary discs collide, combine and eventually build up into planet-sized bodies. However, the finer details of the evolution of these planet-forming discs remain mysterious.

SPHERE is a recent addition to the VLT’s array of instruments and with its combination of novel technologies, it provides a powerful method to directly image the fine details of protoplanetary discs [1]. The interaction between protoplanetary discs and growing planets can shape the discs into various forms: vast rings, spiral arms or shadowed voids. These are of special interest as an unambiguous link between these structures and the sculpting planets is yet to be found; a mystery astronomers are keen to solve. Fortunately, SPHERE’s specialised capabilities make it possible for research teams to observe these striking features of protoplanetary discs directly.

Disc around the star HD 97048

For example, RX J1615 is a young star, which lies in the constellation of Scorpius, 600 light-years from Earth. A team led by the Jos de Boer, of Leiden Observatory in the Netherlands, found a complex system of concentric rings surrounding the young star, forming a shape resembling a titanic version of the rings that encircle Saturn. Such an intricate sculpting of rings in a protoplanetary disc has only been imaged a handful of times before, and even more excitingly, the entire system seems to be only 1.8 million years old. The disc shows hints of being shaped by planets still in the process of formation.

The age of the newly detected protoplanetary disc makes RX J1615 an outstanding system, as most other examples of protoplanetary discs detected so far are relatively old or evolved. De Boer’s unexpected result was quickly echoed by the findings of a team led by Christian Ginski, also of Leiden Observatory. They observed the young star HD 97048, located in the constellation of Chamaeleon, about 500 light-years from Earth. Through painstaking analysis, they found that the juvenile disc around this star has also formed into concentric rings. The symmetry of these two systems is a surprising result, as most protoplanetary systems contain a multitude of asymmetrical spiral arms, voids and vortexes. These discoveries significantly raise the number of known systems with multiple highly symmetrical rings.

Disc around the star HD 135344B

A particularly spectacular example of the more common asymmetric disc was captured by a group of astronomers led by Tomas Stolker of the Anton Pannekoek Institute for Astronomy, the Netherlands. This disc surrounds the star HD 135344B, about 450 light-years away. Although this star has been well-studied in the past, SPHERE allowed the team to see the star’s protoplanetary disc in more detail than ever before. The large central cavity and two prominent spiral arm-like structures are thought to have been created by one or multiple massive protoplanets, destined to become Jupiter-like worlds.

In addition, four dark streaks, apparently shadows thrown by the movement of material within HD 135344B's disc, were observed. Remarkably, one of the streaks noticeably changed in the months between observing periods: a rare example of observing planetary evolution occur in real time, hinting at changes occurring in the inner disc regions that can not be directly detected by SPHERE. As well as producing beautiful images, these flickering shadows provide a unique way of probing the dynamics of innermost disc regions.

As with the concentric rings found by de Boer and Ginski, these observations by Stolker’s team prove that the complex and changing environment of the discs surrounding young stars are still capable of producing surprising new discoveries. By building an impressive body of knowledge about these protoplanetary discs, these teams are stepping closer to understanding how planets shape the discs that form them — and therefore understanding planet formation itself.

Notes:

[1] SPHERE had first light in June 2014. The instrument uses advanced adaptive optics to remove atmospheric distortion, a coronagraph to block most of the light from the central star and a combination of differential imaging and polarimetry to isolate the light from features in the disc.

More information:

The research of de Boer, Ginski and Stolker and their colleagues in the SPHERE consortium is now accepted for publication in the journal Astronomy and Astrophysics. Their papers are entitled: "Direct detection of scattered light gaps in the transitional disk around HD 97048 with VLT/SPHERE"; "Shadows cast on the transition disk of HD 135344B: Multi-wavelength VLT/SPHERE polarimetric differential imaging", and "Multiple rings in the transition disk and companion candidates around RX J1615.3-3255: High contrast imaging with VLT/SPHERE". All three of papers have been created in the framework of the SPHERE GTO program, led by Carsten Dominik, University of Amsterdam.

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

mardi 8 novembre 2016

Image above: Linac 4 during its installation in 2015. This photo was taken as part of the 2015 Photowalk competition (Image: Federica Piccinni/CERN).

CERN’s new linear accelerator (Linac 4) has now accelerated a beam up to its design energy, 160 MeV. This important milestone of the accelerator’s commissioning phase took place on 25 October.

Linac 4 is scheduled to become the source of proton beams for the CERN accelerator complex, including the Large Hadron Collider (LHC) after the long shutdown in 2019-2020. It will replace the existing Linac 2 as the first link in the accelerator chain, which is currently accelerating protons at 50 MeV. The new 30-metre-long accelerator will accelerate hydrogen ions – protons surrounded by two electrons – at 160 MeV, before sending them to the Proton Synchrotron Booster. Here, the ions are stripped of their two electrons to leave only the protons that will be further accelerated before finishing their race in the LHC.

Linac 4 comprises four types of accelerating structures to bring particles in several stages to higher and higher energies. These accelerating structures have been commissioned one by one: in November 2013, the first hydrogen ion beam was accelerated to the energy of 3 MeV and two years after, the Linac 4 accelerator has reached an energy of 50 MeV – the energy Linac 2 runs at. Then, on the 1 July 2016, it crossed the 100 MeV threshold.

Note:

CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 22 Member States.

This month, a single Ariane 5 rocket is set to propel four Galileo satellites into orbit for the navigation constellation’s first-ever quadruple launch. Mission controllers are training intensively for the complex space delivery.

On 17 November, an Ariane 5 will use a new payload dispenser to release four identical satellites into orbit in one go.

Quad sats see space

This will be the eighth Galileo launch, and will bring the number of satellites in space to 18. Once complete, the system will sport 24 operational satellites and a ground network to provide positioning, navigation and timing services.

Four times complex mission control

To date, Soyuz rockets have carried two satellites at a time. This quadruple launch presents several technical challenges, including the new dispenser and the need to establish control over four independent satellites almost simultaneously.The ascent into the medium-altitude orbit will take three and a half hours. Then, after the satellites separate, a combined team from ESA and France’s CNES space agency will take over, establishing control and shepherding them through their early orbits, lasting nine days for one pair and 13 days for the other.

“At the time that the four satellites separate two by two, we’ll have two shifts of the mission team working in the control room at the CNES centre in Toulouse, France, each shift managing two satellites – so it will be an intense period,” says Liviu Stefanov, co-flight director from ESA.

Galileo control room

“This is the same team who conducted the previous Galileo early orbit phases, so we’re familiar with the satellites themselves,” says Hélène Cottet, lead flight director from CNES.

“What’s different this time is managing four satellites, sometimes in sequence and sometimes in parallel. We have concentrated a lot of effort on planning and training for the first few hours in space.”

Since 2011, the joint team have conducted the Galileo initial flight operations alternately from ESA’s centre in Darmstadt, Germany, and the CNES centre in Toulouse.

Target orbit: 23 200 km

Separation will mark the start of a set of critical activities and manoeuvres to ensure the four are ready for handover to the Galileo Control Centre in Oberpfaffenhofen, Germany for the rest of their mission.

This includes ensuring that each have opened their solar wings and are ‘power positive’, establishing a data link via a set of ground stations, conducting extensive health checks and then switching the craft into a stable Earth-pointing mode, ready for subsequent manoeuvres.

Cut-away foursome

Each must make three engine firings at roughly one-day intervals to get onto their ‘drift’ orbits, after which control will be passed from the joint team to the Galileo Control Centre.

“After a few days, we expect things to settle down, and we’ll be able to concentrate on manoeuvring two satellites while babysitting the other two,” says ESA’s Tom Cowell, one of four spacecraft operations managers.

“After handover of the first pair to Oberpfaffenhofen, we can manoeuvre the other two just as we’ve done for previous dual launches.”

Teamwork

Even after handover, specialists will continue determining the orbits and computing manoeuvres to position the satellites in their final orbits at around 23 200 km, expected early in 2017.

Training, simulating, preparing

Since summer, everyone involved in this Galileo launch has worked through multiple simulations, mostly focused on preparing for if things go wrong.

This week, the training will end with an intensive three-day live simulation in Toulouse.

After a network countdown practice on 14 November, the live network countdown for the actual launch will start a couple of hours after midnight on 17 November, with lift off from the European Spaceport in Kourou, French Guiana, set for the same day at 13:06 GMT (14:06 CET).

“It will be a challenge, but having already taken 14 Galileo satellites into orbit, our joint teams are confident of our abilities and skills,” says Hervé Côme, co-flight director from ESA.

“We know we can rely on teamwork and expertise, and we’re looking forward to a smooth lift off for Galileo’s first quad launch.”

The Expedition 50 trio orbiting on the International Space Station is conducting maintenance while getting ready for Earth observations and radiation exposure studies today. In Kazakhstan, three new crew members are waiting as their Soyuz rocket is prepared for launch.

Commander Shane Kimbrough started work on the U.S. segment’s Oxygen Generation System (OGS), which will undergo maintenance throughout the week. Today, Kimbrough tagged up with ground specialists and replaced a hydrogen sensor and will continue to work on OGS through Wednesday. The system is currently shut down due to a low voltage signature within the Hydrogen Orbital Replacement Unit (ORU) that contains the electrolyzing cell stack. The Russian Elektron system is providing oxygen for the crew at this time.

Image above: Middle school children programmed a space station camera to photograph this portion of the Sahara desert seen in western Libya in October. Image Credits: Sally Ride EarthKAM.

The two flight engineers, new cosmonaut Sergey Ryzhikov and veteran station commander Andrey Borisenko, are handing over a set of radiation detectors to Kimbrough. The NASA astronaut, who is on his second trip in space, will install the Radi-N2 detectors in the Destiny laboratory for a week to help doctors understand the radiation risk to crew health and develop protective measures.

Ryzhikov is also setting up a camera that will allow middle school students to photograph targets on Earth and downlink the imagery. The Sally Ride EarthKAM gear will be set up in the Harmony module’s Earth-facing hatch window and use internet-based tools to promote the learning process.

Another trio of Expedition 50 members is counting down to its Nov. 17 launch and two-day trip to the space station from the Baikonur Cosmodrome. Veteran station residents Peggy Whitson of NASA and Oleg Novitskiy of Roscosmos, along with first-time space flyer Thomas Pesquet of the European Space Agency, are in final training before they liftoff aboard the Soyuz MS-03 spacecraft. This will be Whitson’s third station mission and Novitskiy’s second.

Thomas Pesquet, Peggy Whitson and Oleg Novitskiy have tried on their spacesuits and checked out the Soyuz MS-03 spacecraft they will blast off in Nov. 17. After launch, the trio will take a two-day trip to their new home in space where they will live until May. Today, the new crew is participating in flag-raising and tree-planting ceremonies at the Baikonur Cosmodrome launch site.